Metal-insulator-metal (MIM) capacitors are frequently employed in semiconductor dies to provide capacitance to circuitry on the semiconductor die. For example, MIM capacitors are added to semiconductor dies having radio frequency (RF) circuitry to provide by-pass capacitance. RF circuitry is commonly found in devices such as cellular phones. FIG. 1 is a cross-sectional view illustrating a conventional MIM capacitor structure on a semiconductor die.
A MIM capacitor 110 is deposited in trenches 120 of an insulator 104 on a substrate 102. The MIM capacitor 110 includes a metal layer 112, a dielectric layer 114, and a metal layer 116. The dielectric layer 114 separates the metal layer 112 from the metal layer 116. The metal layers 112, 116 are electrodes of the MIM capacitor 110.
Capacitance in a MIM capacitor, such as the MIM capacitor illustrated in FIG. 1, is proportional to the area of the metal electrodes and the thickness of the dielectric layer. The form factor of semiconductor devices is decreasing in size to meet consumer demand for smaller, more portable electronic devices, such as cellular phones. As devices shrink in size, the area available for MIM capacitors decreases resulting in a loss of capacitance. Additionally, the dielectric thickness decreases, resulting in further loss of capacitance.
Thus, there is a need for higher capacitance structures for MIM capacitors.